pain presentation

PAINPAINSubmitted by: Group 74Submitted by: Group 74

Submitted to:Submitted to: Mrs. Mary Jeannie PatrimonioMrs. Mary Jeannie Patrimonio

Pathophysiology Pathophysiology of Painof Pain

Transmission of Pain:Transmission of Pain:

TransductionTransduction TransmissionTransmission PerceptionPerception ModulationModulation

TransductionTransduction Begins when the free nerve endings (nociceptors) Begins when the free nerve endings (nociceptors)

of C fibers and A-delta fibers of primary afferent of C fibers and A-delta fibers of primary afferent neurons respond to noxious stimuli. Nociceptors neurons respond to noxious stimuli. Nociceptors are exposed to noxious stimuli when tissue are exposed to noxious stimuli when tissue damage and inflammation occurs as a result of, damage and inflammation occurs as a result of, for example, trauma, surgery, inflammation, for example, trauma, surgery, inflammation, infection, and ischemia.infection, and ischemia.

Noxious stimuli (with potential to injure tissue) Noxious stimuli (with potential to injure tissue) trigger the release of biochemical mediators (e.g. trigger the release of biochemical mediators (e.g. prostaglandin, bradykinin, serotonin, histamine, prostaglandin, bradykinin, serotonin, histamine, substance P) that sensitize nociceptors.substance P) that sensitize nociceptors.

TransductionTransduction

The nociceptors are distributed in The nociceptors are distributed in the: the:

somatic structures (skin, muscles, somatic structures (skin, muscles, connective tissue, bones, joints);connective tissue, bones, joints);

visceral structures (visceral organs visceral structures (visceral organs such as liver, gastro-intestinal tract).such as liver, gastro-intestinal tract).

TransmissionTransmission

The perception of pain occurs when the nociceptors The perception of pain occurs when the nociceptors are stimulated and transmit signals through sensory are stimulated and transmit signals through sensory neurons in the spinal cord. These neurons release neurons in the spinal cord. These neurons release glutamate, a major exicitory neurotransmitter that glutamate, a major exicitory neurotransmitter that relays signals from one neuron to another. The relays signals from one neuron to another. The signals are sent to the thalamus, in which pain signals are sent to the thalamus, in which pain perception occurs. From the thalamus, the signal perception occurs. From the thalamus, the signal travels to the somatosensory cortex in the cerebrum, travels to the somatosensory cortex in the cerebrum, at which point the individual becomes fully aware of at which point the individual becomes fully aware of the pain.the pain.


There are 2 pathways for There are 2 pathways for transmission of pain in the CNS. transmission of pain in the CNS. These are the neospinothalamic tract These are the neospinothalamic tract (for fast pain) and the (for fast pain) and the paleospinothalamic tract (for slow paleospinothalamic tract (for slow pain).pain).


Fast painFast pain travels via type Aδ fibres to terminate on travels via type Aδ fibres to terminate on lamina I (lamina marginalis) of the dorsal horn. lamina I (lamina marginalis) of the dorsal horn. Second order neurons of the neospinothalamic tract Second order neurons of the neospinothalamic tract then take off and give rise to long fibres which cross then take off and give rise to long fibres which cross the midline through the anterior commisure and pass the midline through the anterior commisure and pass upwards in the contralateral anterolateral columns. upwards in the contralateral anterolateral columns. These fibres then terminate on the Ventrobasal These fibres then terminate on the Ventrobasal Complex (VBC) of the thalamus. From here, third Complex (VBC) of the thalamus. From here, third order neurons communicate with the somatosensory order neurons communicate with the somatosensory cortex. Fast pain can be localised easily if Aδ fibres cortex. Fast pain can be localised easily if Aδ fibres are stimulated together with tactile receptors. are stimulated together with tactile receptors.

TransmissionTransmission Slow painSlow pain is transmitted via slower type C fibres to is transmitted via slower type C fibres to

laminae II and III of the dorsa horns, together known laminae II and III of the dorsa horns, together known as the substantia gelatinosa. Second order neurons as the substantia gelatinosa. Second order neurons take off and terminate in lamina V, also in the dorsal take off and terminate in lamina V, also in the dorsal horn. Third order neurons then join fibres from the horn. Third order neurons then join fibres from the fast pathway, crossing to the opposite side via the fast pathway, crossing to the opposite side via the anterior commisure, and travelling upwards through anterior commisure, and travelling upwards through the anterolateral pathway. These neurons terminate the anterolateral pathway. These neurons terminate widely in the brain stem, with one tenth of fibres widely in the brain stem, with one tenth of fibres stopping in the thalamus, and the rest stopping in the stopping in the thalamus, and the rest stopping in the medulla, pons and mesencephalon. Slow pain is medulla, pons and mesencephalon. Slow pain is poorly localized. poorly localized.

PerceptionPerception

Perception of pain is the awareness—typically Perception of pain is the awareness—typically an uncomfortable awareness—associated with an uncomfortable awareness—associated with a specific area of the body. It depends on the a specific area of the body. It depends on the transmission of pain signals through the transmission of pain signals through the thalamus to the cortex and limbic system. At thalamus to the cortex and limbic system. At this point in pain processing, perception of the this point in pain processing, perception of the pain experience is influenced by social and pain experience is influenced by social and environmental cues, as well as by cultural environmental cues, as well as by cultural conditioning and past personal experiences.conditioning and past personal experiences.

PerceptionPerception

The perception of pain is clearly a complex The perception of pain is clearly a complex process. It usually acts to tells us when we are process. It usually acts to tells us when we are potentially damaging our bodies (acute), but potentially damaging our bodies (acute), but sometimes it serves no purpose (chronic). We can sometimes it serves no purpose (chronic). We can share one another’s pain, but we cannot quantify for share one another’s pain, but we cannot quantify for sure the degree to which another is in pain, making sure the degree to which another is in pain, making pain a very difficult phenomenon to research and pain a very difficult phenomenon to research and understand. The experience of acute pain is often understand. The experience of acute pain is often easier to understand than that of chronic pain because easier to understand than that of chronic pain because we can imagine our own sensation of pain associated we can imagine our own sensation of pain associated with the given pain-inducing situation. with the given pain-inducing situation.

ModulationModulation

The major brainstem regions that produce this The major brainstem regions that produce this effect are located in poorly defined nuclei in effect are located in poorly defined nuclei in the periaqueductal gray matter and the rostral the periaqueductal gray matter and the rostral medulla. Electrical stimulation at each of these medulla. Electrical stimulation at each of these sites in experimental animals not only sites in experimental animals not only produces analgesia by behavioral criteria, but produces analgesia by behavioral criteria, but also demonstrably inhibits the activity of also demonstrably inhibits the activity of nociceptive projection neurons in the dorsal nociceptive projection neurons in the dorsal horn of the spinal cord.horn of the spinal cord.

ModulationModulation

Understanding the central modulation of pain Understanding the central modulation of pain perception (on which the placebo effect is perception (on which the placebo effect is presumably based) was greatly advanced by the presumably based) was greatly advanced by the finding that electrical or pharmacological stimulation finding that electrical or pharmacological stimulation of certain regions of the midbrain produces relief of of certain regions of the midbrain produces relief of pain . This analgesic effect arises from activation of pain . This analgesic effect arises from activation of descending pain-modulating pathways that project, descending pain-modulating pathways that project, via the medulla, to neurons in the dorsal horn—via the medulla, to neurons in the dorsal horn—particularly in Rexed's lamina II—that control the particularly in Rexed's lamina II—that control the ascending information in the nociceptive system. ascending information in the nociceptive system.

Theories of PainTheories of Pain

Affect TheoryAffect Theory Pattern TheoryPattern Theory Specificity TheorySpecificity Theory Gate Control theoryGate Control theory

Affect TheoryAffect Theory

In psychology, affect is an emotion or subjectively In psychology, affect is an emotion or subjectively experienced feeling. experienced feeling. Affect theoryAffect theory is a branch of is a branch of psychoanalysis that attempts to organize affects into psychoanalysis that attempts to organize affects into discrete categories and connect each one with its discrete categories and connect each one with its typical response. So, for example, the affect of typical response. So, for example, the affect of joyjoy is is observed through the reaction of observed through the reaction of smilingsmiling. These . These affects can be identified through immediate facial affects can be identified through immediate facial reactions that people have to a stimulus, typically reactions that people have to a stimulus, typically well before they could process any real response to well before they could process any real response to the stimulus. the stimulus.


Tomkins (1962) stressed that each affect Tomkins (1962) stressed that each affect functions as an amplifier that calls attention to functions as an amplifier that calls attention to anything with which it becomes associated or anything with which it becomes associated or "coassembled." There are nine of these "coassembled." There are nine of these nonspecific amplifiers, and therefore nine nonspecific amplifiers, and therefore nine different ways that affect can, by this different ways that affect can, by this amplification, increase the likelihood that the amplification, increase the likelihood that the information with which it has been assembled information with which it has been assembled will be used by the organism. will be used by the organism.

Affect TheoryAffect Theory Interest-excitement and enjoyment-joy, the two Interest-excitement and enjoyment-joy, the two

positive affects, are counterbalanced by six decidedly positive affects, are counterbalanced by six decidedly negative affects (fear-terror, distress-anguish, anger-negative affects (fear-terror, distress-anguish, anger-rage, dissmell, disgust, and shame-humiliation), all of rage, dissmell, disgust, and shame-humiliation), all of which may be halted instantly by surprise-startle, an which may be halted instantly by surprise-startle, an affect that is too brief to have either a positive or a affect that is too brief to have either a positive or a negative flavor. By their effects on bodily structures negative flavor. By their effects on bodily structures that evolved for other reasons (heart rate, voice, facial that evolved for other reasons (heart rate, voice, facial musculature, sweat, etc.) these nine innate affects call musculature, sweat, etc.) these nine innate affects call attention to their triggering source in nine quite attention to their triggering source in nine quite different ways. different ways.


All of these sites of action for innate affect are All of these sites of action for innate affect are quite ordinary biological mechanisms set off quite ordinary biological mechanisms set off by well known groups of neurotransmitters. by well known groups of neurotransmitters. Since these sites of action can be set off under Since these sites of action can be set off under the control of affect programs, we infer that the control of affect programs, we infer that one of the properties of the affect system is to one of the properties of the affect system is to direct the release of neurotransmitters. direct the release of neurotransmitters.


If some aberration of neurotransmitter If some aberration of neurotransmitter metabolism causes things to happen at the sites metabolism causes things to happen at the sites of action normally associated with one or of action normally associated with one or another innate affect, we humans are likely to another innate affect, we humans are likely to mistake the pattern of actions so released as mistake the pattern of actions so released as the gestalt normally associated with a normal the gestalt normally associated with a normal affect. affect.

Pattern TheoryPattern Theory

Pattern Pattern theories consider that peripheral theories consider that peripheral sensory receptors, responding to touch, sensory receptors, responding to touch, warmth and other non-damaging as well as to warmth and other non-damaging as well as to damaging stimuli, give rise to non-painful or damaging stimuli, give rise to non-painful or painful experiences as a result of differences in painful experiences as a result of differences in the patterns [in time] of the signals sent the patterns [in time] of the signals sent through the nervous system.through the nervous system.


Goldschneider (1920) proposed that there is no Goldschneider (1920) proposed that there is no separate system for perceiving pain, and the separate system for perceiving pain, and the receptors for pain are shared with other senses, receptors for pain are shared with other senses, such as of touch. According to this view, such as of touch. According to this view, people feel pain when certain patterns of people feel pain when certain patterns of neural activity occur, such as when appropriate neural activity occur, such as when appropriate types of activity reach excessively high levels types of activity reach excessively high levels in the brain. in the brain.


These patterns occur only with intense These patterns occur only with intense stimulation. Because strong and mild stimuli stimulation. Because strong and mild stimuli of the same sense modality produce different of the same sense modality produce different patterns of neural activity, being hit hard feels patterns of neural activity, being hit hard feels painful, but being caressed does not. painful, but being caressed does not.

Specificity TheorySpecificity Theory

There is a special system of nerves which carries There is a special system of nerves which carries messaged from pain receptors in the skin to a pain messaged from pain receptors in the skin to a pain centre in the brain.centre in the brain.

One points of favour is that there are specialized One points of favour is that there are specialized receptors in the skin for different sensations like heat receptors in the skin for different sensations like heat and touch.and touch.

Specific stimulus has a specific receptor which goes Specific stimulus has a specific receptor which goes to a location in the brainto a location in the brain

Specificity TheorySpecificity Theory

The specific location identifies the pain’s The specific location identifies the pain’s qualityquality

Psychological pain : Phantom Limb PainPsychological pain : Phantom Limb Pain

Gate Control theoryGate Control theory

To explain why thoughts and emotions To explain why thoughts and emotions influence pain perception, Ronald Melzack and influence pain perception, Ronald Melzack and Patrick Wall proposed that a gating mechanism Patrick Wall proposed that a gating mechanism exists within the dorsal horn of the spinal cord. exists within the dorsal horn of the spinal cord. Small Small nervenerve fibers fibers (pain receptors) and (pain receptors) and large large nerve fibersnerve fibers ("normal" receptors) synapse on ("normal" receptors) synapse on projection cellsprojection cells (P), which go up the (P), which go up the spinothalamic tract to the spinothalamic tract to the brainbrain, and , and inhibitory inhibitory interneuronsinterneurons (I) within the dorsal horn. (I) within the dorsal horn.

Gate Control Theory Gate Control Theory

The interplay among these connections The interplay among these connections determines when painful stimuli go to the determines when painful stimuli go to the brain:brain:

When no input comes in, the inhibitory neuron When no input comes in, the inhibitory neuron prevents the projection neuron from sending prevents the projection neuron from sending signals to the brain (gate is closed). signals to the brain (gate is closed).

Gate Control TheoryGate Control Theory

Normal somatosensory input happens when Normal somatosensory input happens when there is more large-fiber stimulation (or only there is more large-fiber stimulation (or only large-fiber stimulation). Both the inhibitory large-fiber stimulation). Both the inhibitory neuron and the projection neuron are neuron and the projection neuron are stimulated, but the inhibitory neuron prevents stimulated, but the inhibitory neuron prevents the projection neuron from sending signals to the projection neuron from sending signals to the brain (gate is closed). the brain (gate is closed).


Nociception (pain reception) happens when Nociception (pain reception) happens when there is more small-fiber stimulation or only there is more small-fiber stimulation or only small-fiber stimulation. This inactivates the small-fiber stimulation. This inactivates the inhibitory neuron, and the projection neuron inhibitory neuron, and the projection neuron sends signals to the brain informing it of pain sends signals to the brain informing it of pain (gate is open). (gate is open).

SALAMAT SA PAKIKINIG!!!SALAMAT SA PAKIKINIG!!!

pain presentation

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